1. Field
The present invention relates generally to image transmission systems and, more specifically, to analyzing non-coherent optical bundles for use in image transmission systems.
2. Description
Flexible borescopes, endoscopes, and other optical inspection devices typically use coherent optical bundles to transmit images from one location to another. A coherent optical bundle is a collection of glass fibers wherein the relative position of the fibers within the bundle at each end of the bundle is identical. The glass fibers are used to transmit light from one end to the other end. A coherent optical bundle is often the most expensive part of an optical inspection device. It may contain more than 100,000 individual glass fibers, perfectly arranged in the same matrix position from end to end of a long fiber bundle. In some cases, the length of the bundle is four to five meters. In a coherent optical bundle, it is important that the relative position of the fibers at each end of the bundle be identical in order to transmit an image from one end to the other without scrambling it. In essence, each fiber of the bundle is similar to a pixel in a digital image.
FIG. 1 is a schematic example of a known, very small coherent optical bundle. It includes only a few fibers in order to simplify the example. The fibers of the bundle may be arranged in a matrix represented as rows and columns. In this example, there are three rows and three columns in the matrix. Each digit shown in FIG. 1 represents one glass fiber in the bundle. The fibers (e.g., the digits) are shown in this simple example to represent a rectangular object that may be viewed by a borescope or other optical inspection device. Each fiber transmits a portion of the image representing the object being viewed. If the entire image is to be transmitted correctly along the optical bundle from a sending end to a receiving end, each fiber (e.g., a digit) should be configured in a known relationship in the matrix on both ends of the long optical bundle. Otherwise, the image will be garbled or scrambled when it is received at the receiving end.
Coherent optical bundles work reasonably well in a variety of image transmission devices. However, they are typically quite expensive due to the coherency requirement. In contrast, non-coherent optical bundles are much cheaper. A non-coherent optical bundle is a collection of glass fibers where the position of any fiber at one end of the bundle is not necessarily the same as the position of the fiber at the other end. In fact, the positioning of the fibers within the bundle is typically somewhat random. This does not result in a problem when the bundle is used merely to transmit light from one end to the other for illumination purposes. However, if the non-coherent optical bundle is used for image transmission, the images end up being scrambled at the receiving end, and therefore the transmitted images are of minimal utility. Thus, there is a need in the art to overcome these and other problems by a method of using non-coherent optical bundles for image transmission, in order to reduce the cost of optical inspection devices, for example.
An embodiment of the present invention is a method of using a non-coherent optical bundle having a plurality of fibers for image transmission. The method includes analyzing a configuration of the fibers of the non-coherent optical bundle to generate a mapping function, obtaining image data at a sending end of the non-coherent optical bundle, transmitting the image data over the non-coherent optical bundle, the image data being scrambled during transmission to produce scrambled image data at a receiving end of the non-coherent optical bundle, and applying the mapping function to the scrambled image data to reproduce the image data.